The present invention is directed to therapeutic fluid filled insoles, and more particularly to insole bladders having fluid flow directing and restricting members within the bladder with the purpose of achieving improved medical benefits and directional stability to the users.
Fluid filled insoles have long been known in the art, see for example, U.S. Pat. No. 4,567,677 to James Zona, U.S. Pat. No. 4,115,934 to Hall, U.S. Pat. No. 4,123,855 to Thedford, U.S. Pat. No. 2,080,469 to Gilbert and U.S. Design Pat. No. D246,486 to John W. Nickel. Prior art insoles commonly comprise a bladder having an upper layer and a lower layer. The two layers are welded together at their marginal periphery. The bladder has a planar, foot-shaped configuration, which includes a forefoot region, a hindfoot region, and a midfoot region there between. The bladder is filled with a fluid, such as water or air. The broader technical functions of fluid filled insoles are well documented, whereas the medical benefits are only partly documented. It is not generally known that fluid filled insoles may be designed to accomplish specific medical benefits. The known technical functions include cushioning of the feet by a massaging action on the plantar surface of the feet due to movement of the fluid within the bladder, thus achieving comfort to the user.
The fluid filled insoles of the prior art have not been entirely satisfactory, however, in the area of providing demonstrative medical benefits, neither as a device for eliminating or relieving fatigue in the lower extremities by providing stress distribution and activation of the venous pump function nor for achieving directional stability to the user when wearing the insole. Existing prior art insoles have little or no means for controlling both the transverse and longitudinal flow and the rate of fluid flow within the insole nor for matching the flow of fluid to the anatomical structure of the foot. As a user walks, the user's weight is initially applied to heel, and then is transferred to the ball of the foot. This causes the fluid within the bladder to move, respectively, from the hindfoot region to the forefoot region and then back towards the hindfoot again. Without means for directing fluid flow anatomically within the bladder, the fluid will flow uncontrollably and thus causing directional instability to the user when wearing the insole. Without means for controlling and restricting the rate of fluid flow vis-a-vis viscosity and density of the fluid, the user's feet will simply jump through the fluid, and thus the fluid insole has no cushioning or massaging effect.
Some prior art devices, such as the insole of the Zona patent, have attempted to regulate flow from the hindfoot region to forefoot region and vice versa by placing flow restricting means in the midfoot area of the bladder. These flow restricting devices are only partly effective, however, since they neither match the anatomical structure of the foot nor regulate or direct the flow within the forefoot or hindfoot regions of the bladder to achieve directional stability and local stress distribution. In addition, the midfoot flow restricting means are not matched to the longitudinal medial anatomical structure of the arch. Matching the anatomical structure of the foot to the location, direction, quantity and duration of fluid flow are important to achieve therapeutic benefits, stress distribution and directional stability.
Some prior art insoles, as shown for example in the Hall or Nickel patents have attempted to regulate fluid flow within the forefoot and hindfoot regions. But, these efforts have not been satisfactory because the fluid flow is not matched to the anatomical structure of said regions, but rather directed to the outer, medial and lateral, margins of the insole, away from the areas of the foot where fluid massaging action and pressure distribution is required when considering the physiology and anatomy of the foot.
The Thedford patent has also attempted to regulate fluid flow within the forefoot and hindfoot regions. These teachings have not been satisfactory because the fluid flow is neither adapted to the anatomical structure of the foot nor arranged in a fashion that achieves directional stability to the user during the flow of fluid within the insole. Further, the Thedford patent teaches prohibition or blocking of longitudinal flow within the bladder, redirecting the flow in a transverse direction.
The Gilbert patent has attempted to regulate fluid flow by randomly dispersing flow restrictors across the entire surface of the insole, which, again, does neither match the anatomical structure of the foot nor achieve directional stability. The Gilbert patent does not specify any particular arrangement of flow restrictors or fluid flow, but teaches that the "spots" "may be disposed at any desirable location with any desirable frequency" which makes flow control indefinite. Further, the Gilbert patent permits air to shift in any direction and partly arranges flow restricting means to block longitudinal flow.
Many prior art insoles are filled with ordinary water or other fluids that not only quickly evaporate and thus significantly reduces the industrial applicability (life time) of the insole, but also develops bacteria and/or other microorganisms, causing the fluid to become toxic and thus environmentally unsafe. In addition, existing prior art insoles do not consider the fluid itself as a flow restricting means and thus significantly limits the therapeutic value of the insole by allowing the fluid to flow at a rate that cannot satisfactorily provide pressure distribution.
Finally, none of the prior art insoles considers local pressure distribution within the midfoot, forefoot and hindfoot regions of the bladder by directing, controlling and restricting the flow of fluid within the midfoot, forefoot and hindfoot regions. This lacking consideration significantly limits the medical and therapeutic applications of the prior art insoles. It would be desirable to have a fluid filled insole that (i) controls and directs the fluid to match the anatomical structure of the foot and achieve directional stability to the user wearing the insole, (ii) maximizes even pressure distribution to minimize peak pressures on the foot, both across the entire area of the foot and within each of the hindfoot, midfoot and forefoot regions, (iii) ensures minimum evaporation of the fluid to maximize the life time of the insole, (iv) provides a fluid that is environmentally safe, and (v) devises a fluid that functions as a flow restricting means vis-a-vis the density and viscosity of said fluid, and which otherwise overcomes the limitations inherent in the prior art.